Composition regulation of semiconductors can engineer the band gap and thus tune the optical properties. For effective utilization of orange emitting phosphors in color conversion applications blue excitation is necessary. Here in this work, absorption and photoluminescence spectroscopic measurements have been done to study the variation in band gap energy by changing the composition of ZnxCd1-xS nanocrystals. Further, ternary Mn doped ZnxCd1-xS semiconductor nanocrystals have been synthesized via an aqueous route over a wide composition range by adjusting the molar ratio of precursors which leads to tunable bandgap, thus propagate the progressive growth of light absorption and photoluminescence spectra. The variation in tunability of bandgap is due to the change in Cd/Zn ratio. By changing Cd/Zn ratio excitation wavelength shifts from UV to blue colour. Copyright © 2017 VBRI Press.